Long Term Evolution (LTE) is the last step toward the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile telephone networks and provides for an end-to-end Internet Protocol (IP) service delivery of media. Currently, LTE comprises a set of enhancements to the Universal Mobile Telecommunications System (UMTS), which is described in a suite of Technical Specifications (TS) developed within and publicized by 3rd Generation Partnership Project (3GPP), with the most recent version of the 3GPP TSs being published in June 2010 as a revised “Release 9” (with Release 10 currently being developed).
LTE, in part, provides for a flat IP-based network architecture designed to ensure support for, and mobility between, some legacy or non-3GPP systems such as, for instance, GPRS (general packet radio service) and WiMAX (Worldwide Interoperability for Microwave Access). Some of the main advantages with LTE are high throughput, low latency, plug and play, FDD (frequency-division duplexing) and TDD (time-division duplexing) in the same platform, improved end user experience, simple architecture resulting in low operating costs, and interoperability with older standard wireless technologies such as GSM (Global Systems for Mobile Communications), CdmaOne™, W-CDMA (UMTS), and CDMA2000®.
Many major carriers in the United States (US) and several worldwide carriers have started to convert their networks to LTE. In addition, public safety agencies in the US (including US Intelligence Services) have endorsed LTE as the preferred technology for the new 700 MHz public safety radio band. However, LTE systems do not currently provide some of the benefits of legacy systems for public safety applications.
For example, some public safety applications (for instance mission critical applications using push-to-talk), experience fast set-up times for communications among multiple user equipment using the legacy communication systems, which are not currently realizable on LTE systems. Since such applications are widely deployed, public safety customers will continue to expect these faster call set-up times even on the LTE systems.
Thus, there exists a need for methods of reducing set-up time for communications among multiple user equipment in an LTE communication system.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. Apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the various embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.